A wireless communication device comprises various high frequency elements such as an antenna, a filter, an RF switch, a power amplifier, an RF-IC and a balun. Of these elements, a resonant element such as an antenna or a filter handles (transmits) an unbalanced signal which is based on a ground potential, whereas an RF-IC which generates or processes a high frequency signal handles (transmits) a balanced signal. Accordingly, when electromagnetically connecting these two elements, a balun that functions as an unbalanced-balanced converter is used.
Recently, there is a demand for smaller and thinner baluns for use in wireless LAN devices, mobile communication devices such as a mobile phone and a portable terminal in order to meet the needs for miniaturization of these devices. As one of such thin film baluns, for example, Patent Document 1 proposes a chip-type balun having a coil lamination structure.    [Patent Document 1] Japanese laid-open publication No. 07-176918 (JP7-176918A)
However, in the configuration of a chip-type balun disclosed in the above patent document 1, a desired balanced characteristic cannot be sufficiently obtained in a signal frequency that is to be converted while maintaining miniaturization of the balun, and there is a problem in that the characteristic of the balun is insufficient as a balun for high frequency used in mobile phones, etc.